Datasheet Linear Technology LT8309IS5#PBF

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  Increase Current Capability and Simplify Thermal Design of Flyback Converters with Secondary-Side Synchronous Rectifier Driver in a 5-Pin SOT-23 &mdash LT Journal
  PDF, 376 Kb, File published: Jan 6, 2014
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  Increase Current Capability and Simplify Thermal Design
  of Flyback Converters with Secondary-Side Synchronous
  Rectifier Driver in a 5-Pin SOT-23
  Wei Gu In a flyback converter, current levels in high current applications are constrained
  by heat produced in the output rectifier diode. The clear way to lift this restriction
  is to replace the diode with a much lower voltage drop MOSFET, significantly
  reducing heat produced in the rectifier—reduced heat dissipation increases output
  current capability and efficiency, and simplifies thermal design. The LT8309 is a
  secondary-side synchronous MOSFET driver that replicates the behavior of the
  output diode by sensing the drain-to-source voltage of the MOSFET to determine
  if should be on or off, allowing it to replace a less efficient rectifier diode.
  The LT8309 can be combined with any
  of Linear’s line of no-opto boundarymode flyback ICs (such as the LT3748
  primary side controller) to produce high
  performance isolated power supplies
  with a minimal number of components.
  5V, 8A ISOLATED SUPPLY Figure 1 shows a low voltage, high
  current, low parts count flyback
  supply. The traditional output diode is
  replaced by an ideal diode consisting
  of the LT8309, a MOSFET and a few
  small external components.
  For a MOSFET to act as a diode it must …

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Manufacturer's Classification

• Power Management > Switching Regulator > Flyback, Forward and Isolated Controllers
• Space & Harsh Environment > Extended Temperature Plastic (H & MP) > Extended Temperature (H & MP) Power Management
• Power Management > Power Control > Secondary Side Controllers

Other Names:

LT8309IS5PBF, LT8309IS5 PBF